The Air Up There

Spending hours on a crowded plane seems like the perfect way to pick up a cold or flu. But research shows that airliners pose less of a health risk than you might thinkand new technology promises to make flying even healthier

Every winter, legions of healthy travelers board airplanes wondering if they'll still be well when they walk off, after spending hours packed shoulder to shoulder with dozensor even hundredsof other passengers, some of whom are likely to be suffering from a cold or the flu.* But there's good reason to take heart (and take to the skies): Several scientific studies show that, in terms of the spread of contagious bugs, airplanes are healthier environments than is commonly believed. While it's true that the germs which cause colds and flu can be passed from person to person through coughs and sneezes, research indicates that you need to be sitting very close to a sick passengerusually within two rowsand for longer than eight hours to significantly increase your chances of contracting an illness. "There is a heightened risk of infection when you enter a confined space such as an aircraft or subway, but a plane is a much safer place because of the ventilation system," says Dr. Mark Gendreau, an emergency and aviation medicine expert at the Lahey Clinic in Burlington, Massachusetts. On average, cabin air is completely refreshed 20 times per hour, compared with just 12 times per hour in an office building. On most aircraft, air is also circulated through hospital-grade HEPA filters, which remove 99.97 percent of bacteria, as well as the airborne particles that viruses use for transport (many regional jets lack these filters). Additionally, cabins are divided into separate ventilation sections about every seven rows of seats, which means that you share air only with those in your immediate environment and not with the guy who's coughing up a lung ten rows back. When the plane is on the ground, however, air circulation in the cabin can be greatly reduced.

The most common way to pick up a bug when flying, experts say, is from a contaminated surfacetray tables, lavatory doors, and latches on overhead bins are loaded with viruses and bacteria. "When I travel, I become very compulsive and even wipe the tray table with an alcohol-based hand sanitizer," says Dr. Gendreau.

The achy, icky feeling many fliers get after spending hours in the air usually has nothing to do with colds or flu and everything to do with the bone-dry, oxygen-thin atmosphere of the cabin. But new developments in aircraft manufacturing and air filtration promise to make flying more comfortable and to reduce even further the chance that you'll catch something from a fellow passenger.

Most planes cruise at 35,000 feet or higher, but since passengers need to breathe, aircraft cabins are pressurized to about 8,000 feet above sea level, which is all their aluminum skins can safely endure. It's also a higher altitude than most people are used to (studies show that discomfort begins for vulnerable passengers once the cabin pressure exceeds 6,000 feet). "Some people are effectively suffering from altitude sickness in flight," says Condé Nast Traveler Medical Affairs Correspondent Dr. Richard Dawood. The next generation of planes will be built from composite materialsplastics reinforced with carbon fiberand will usher in a new era of comfort. The much-delayed Boeing 787 Dreamliner, the world's first aircraft constructed almost entirely of composites, promises to offer relief not only from altitude sickness but also from the burning eyes and swollen nasal passages many fliers experience. "One of the problems of aluminum airplanes is the danger of metal corrosion," says Ken Price, an interiors expert at Boeing. Which, he explains, is why it is as dry as a desert inside an aircraft, with humidity levels sometimes dipping below ten percent. The 787 will have "much more humidity than any current plane," Price says, because moisture doesn't pose a threat to the composite materials it's made from. Airbus's new mid-sized wide-body, the A350, isn't expected to be launched for another few years, but it too will use more composite materials, which should allow for relief from cabin dryness. In the meantime, some fliers are already enjoying the benefits of new construction materials: The recently introduced Airbus A380 double-decker behemoth is partly built from plastic, allowing it to be pressurized to 5,000 feet and deliver a more comfortable ride.

The latest development in cabin air quality is a new purification technology being tested by British aerospace giant BAE Systems. AirManager, developed by the U.K. firm Quest International, uses a patented technology known as "non-thermal plasma" to eliminate not only germs and particles but also all the viruses, impurities, and foul odors that HEPA filters cannot. AirManager underwent four years of testing aboard the fleets of eight European regional carriers and has been cleared by European regulators for installation on BAE's own 146-series of smaller jets. The Federal Aviation Administration says that it is watching the development and that AirManager could replace current filtration systems once they reach the end of their useful life. However, since the new system could cost about ten times more than HEPA filters ($80,000 to equip a 737, for example), it's not likely that airlines will rush to install them ahead of schedule.

Updated April 28, 2011: A reference to 2009's outbreak of swine flu has been deleted.